The present invention relates to a method for producing a joint between a hollow profile made from steel and a component made from an aluminum material. The present invention also relates to a hollow profile joint of a hollow profile made from steel with a component made from an aluminum material.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
In the context of the present specification and claims, the term “positive fit” or “positively” is meant to indicate a form-fitting or interlocking engagement between components, and the term “non-positive fit” or “non-positively” is meant to indicate a force-fitting engagement or an interference fit between components.
Frequently, non-thermal joining methods employing, for example, rivets or screws are used for joining components made from steel and an aluminum material. The different components are here joined by a positive lock produced by the rivet and the screw, respectively. However, the strength of such joint is limited due to the point-wise force transfer.
The realization of steel-aluminum hybrid components has great potential for weight reduction and improvement of the product properties, in particular of the vehicle body. The aforedescribed cold joining methods, for example riveting or adhesive techniques, do not lead to the required stability.
Conventional joint-welding methods are known which make it possible to realize a material weld in spite of the different melting points of the two alloys, steel and aluminum. These methods are known in the state-of-the-art as braze welding processes. Only the material constituent of the aluminum component is melted, and the component made from steel is materially connected with the aluminum material by a brazing process. When using a brazing process, the steel component is coated before the braze welding process. Such coating can be implemented, for example, by galvanizing. The galvanized steel component is wetted by the welding deposit and the intermetallic phases can be reduced to a small amount. However, these material joints also have only limited strength.
Also disadvantageous is the existence of a gap between the cast aluminum part and the steel pipe. Ambient air may enter the melt through this gap during the welding process, resulting in a weld of poor quality and hence low strength. Moreover, moisture can reach the steel-aluminum transition during the operation, causing additional gap corrosion.
It would therefore be desirable and advantageous to address this problem and to obviate other prior art shortcomings by providing a method for producing a joint between two components with different material properties, which has exceptionally high strength and a long service life. It would also be desirable to provide a corresponding hollow profile joint.